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It is often said that in general relativity time does not exist. This is because the Einstein equations generate motion in time that is a symmetry of the theory, not true time evolution. In quantum gravity, the timelessness of general relativity clashes with time in quantum theory and leads to the ``problem of time'' which, in its various forms, is the main obstacle to a successful quantum theory of gravity. I argue that the problem of time is a paradox, stemming from an unstated faulty premise. Our faulty assumption is that space is real. I propose that what does not fundamentally exist is not time but space, geometry and gravity. The quantum theory of gravity will be spaceless, not timeless. If we are willing to throw out space, we can keep time and the trade is worth it.

Author Bio

Fotini Markopoulou works on the problem of quantum gravity. Her work explores the microscopic structure of spacetime and the role of causality at very high energies. Born in Athens, Greece, she received her Ph.D. in theoretical physics from Imperial College, London. She held postdoctoral positions at Pennsylvania State University, Imperial College, and the Albert Einstein/Max Planck Institute for Gravitational Physics, Berlin, before moving to Canada in 2001 as a founding member and faculty at the Perimeter Institute for Theoretical Physics in Canada, a research institute devoted to foundational issues in theoretical physics.

may you please explain who time is related to measureble quantities according to your approach? It seems that you consider time as something intrinsic without facing at all the point that you may define time only in a system which include a clock assumed to be calable to measure it.

You don't need to call quantum gravity to say that time is not a fundamental gravity: the two clocks arguments is very simple and is not theory dependent: it is a metrologic problem. In your work it seems that it is possible to speak about time as something distinct from clocks: this is a very severe loop, since you have a concept of time only because you have clocks (daily sun, atomic clocks...). Can you please explain what is a clock and how it is realted to time in your approach?

Thank you

John

Mark Stuckey wrote on Dec. 3, 2008 @ 01:15 GMT

Dear Fotini,

If you've read our essay (Time...Relational Blockworld), you know that we represent a very similar approach -- we have RaumZeitMaterie and you have muatter. So, of course, I enjoyed your essay :-)

One of the main differences in our approaches is that muatter manifests only at high temps, dissolving into the usual geometry at low temps (if I understand correctly). We actually go the other way so that we can use the weird connectedness of RaumZeitMaterie to explain QM non-locality/entanglement. Do you see muatter bearing on QM non-locality even at the low temps of such phenomena? I know you state at the end that you don't have quantum mechanics, so this is perhaps unfair, but I'm wondering if you might speculate nonetheless.

Great essay, Fotini. You have my vote!

Mark

Dimi Chakalov wrote on Dec. 3, 2008 @ 03:15 GMT

Dear Fotini,

You claim that, in quantum gravity, "[mu]atter becomes both geometry and matter" (p. 8), but because in GR "matter tells spacetime how to curve and spacetime tells matter where to go", it is obvious that your wristwatch cannot "read" the non-linear dynamics of negotiation between the two sides in Einstein Equations (p. 1). Perhaps your (inanimate) wristwatch will inevitably halt by trying to "read" such (global) time, hence the illusion about some "problem of time". Check out a Gedankenexperiment from Wikipedia here.

Dr. E (The Real McCoy) wrote on Dec. 3, 2008 @ 20:05 GMT

Hello Fotini,

Loved the paper!

You begin with, "It is often said that in general relativity time does not exist. This is because the Einstein equations generate motion in time that is a symmetry of the theory, not true time evolution."

Moving Dimensions Theory, with its simple postualte that the fourth dimension is expanding relative to the three spatial dimensions: dx4/dt=ic,...

You begin with, "It is often said that in general relativity time does not exist. This is because the Einstein equations generate motion in time that is a symmetry of the theory, not true time evolution."

Moving Dimensions Theory, with its simple postualte that the fourth dimension is expanding relative to the three spatial dimensions: dx4/dt=ic, provides a foundation for all of relativity; while also weaving change into the fundamental fabric of spacetime for the first time in all of relativity.

It is dangerous to talk about the "The paradox of time in quantum gravity," when quantum gravity exists neither in theory nor in practice. It would be like trying to make a science out of the paradox of the flying spaghetti monster.

You write, "The quantum theory of gravity will be spaceless, not timeless."

MDT, on the other hand, proposes that we keep space, time, physics, logic, reason, and simple postulates and equations unifying diverse *physical* phenomena, while also ridding ourselves of things that don't make sense, such as the block universe and frozen time.

You would enjoy my paper!

http://fqxi.org/community/forum/topic/238

"In his 1912 Manuscript on Relativity, Einstein never stated that time is the fourth dimension, but rather he wrote x4 = ict. The fourth dimension is not time, but ict. Despite this, prominent physicists have oft equated time and the fourth dimension, leading to un-resolvable paradoxes and confusion regarding time’s physical nature, as physicists mistakenly projected properties of the three spatial dimensions onto a time dimension, resulting in curious concepts including frozen time and block universes in which the past and future are omni-present, thusly denying free will, while implying the possibility of time travel into the past, which visitors from the future have yet to verify. Beginning with the postulate that time is an emergent phenomenon resulting from a fourth dimension expanding relative to the three spatial dimensions at the rate of c, diverse phenomena from relativity, quantum mechanics, and statistical mechanics are accounted for. Time dilation, the equivalence of mass and energy, nonlocality, wave-particle duality, and entropy are shown to arise from a common, deeper physical reality expressed with dx4/dt=ic. This postulate and equation, from which Einstein’s relativity is derived, presents a fundamental model accounting for the emergence of time, the constant velocity of light, the fact that the maximum velocity is c, and the fact that c is independent of the velocity of the source, as photons are but matter surfing a fourth expanding dimension. In general relativity, Einstein showed that the dimensions themselves could bend, curve, and move. The present theory extends this principle, postulating that the fourth dimension is moving independently of the three spatial dimensions, distributing locality and fathering time. This physical model underlies and accounts for time in quantum mechanics, relativity, and statistical mechanics, as well as entropy, the universe’s expansion, and time’s arrows and assymetries across all realms."

Time as an Emergent Phenomenon: Traveling Back to the Heroic Age of Physics by Elliot McGucken

Great essay. My question is really for both you and Olaf Dryer in that you both begin with a pre-geometric base, the rejection of the dualism between geometry and matter and a Lorentzian take on GR (and thus SR). Question one: while you both get out of the problem of time (Wheeler-DeWitt), do you think that the Lorentz interpretation is sufficient to get out of the blockworld (BW)implication of the relativity of simultaneity? That is, do you think the Lorentz interpretation somehow yields a preferred frame at the level of spacetime itself? Of course Wheeler-DeWitt is more radically timeless than the BW of M4, but I'm curious if you are additionally alleging not only to recover GR or M4 from your pre-geometric base but also a preferred frame that negates BW? If so, how does this story go and does the preferred frame map onto the experience of the present moment in some way? Question two: am I right in thinking that at bottom you both have Causality and/or a pre-geometric analogue of a preferred frame? I gather this is the norm, but why isn't this considered cheating? Is it surprising that one recovers SR if one starts with Causality?

Part of the reason I ask these questions is that we also have a pre-geometric base that negates the dualism between geometry and matter but by contrast we begin with a discrete graph theoretic approach {a discrete path integral formalism, though we don't interpret it as path integrals as such} and we recover the entire BW of spacetime. That is, our pre-geometric account isn't dynamical at all (and we assume neither Causality or a preferred frame)and what we recover is the BW. We started with a time-symmetric (acausal and adynamical) interpretation of QM called the relational blockworld and worked backwards to QG so we have a solid story about recovering QM from our pre-geometric base. In any case, I'm hoping you guys will look at our essay (see below) and offer comments as there is much to discuss in our similarities and differences.

"It is photons bouncing off the paper and hitting your retina while you read this essay that make this sentence be part of your past." --- this seems a very particle-oriented description of what an event is. Is this really how you intend to present an event? You leave events much less articulated in your gr-qc/9811053, for example. The sense seems to be that events are fundamental mathematical objects (I almost wrote point-like, but that must be too geometrical an idea to be right), but then I'm not sure how you make empirical contact with actually recorded observation events such as a CCD signal, a proportional counter signal, or a firing of an optic nerve, which are more-or-less macroscopic? Indeed, insofar as a recorded observation event is associated with a macroscopic apparatus, an eye, etc., it has a place in space-time, which your events do not, leading me back to wondering whether you *really* don't mean to say "It is photons bouncing off the paper and hitting your retina while you read this essay that make this sentence be part of your past" as an example of an event?

Aleksandar Mikovic wrote on Dec. 6, 2008 @ 10:56 GMT

Dear Fotini,

I find your ideas on space and time quite close to mine.

In my approach (see the essay "Temporal Platonic Metaphysics") I describe our Universe as an ordered sequence of colored graphs, which correspond to fundamental constituents of space and matter and their relations. This ordered set of graphs represents a timeless history, and time is introduced by requiring that there is a moving instant of now along the graphs of the Universe history. What you refere to as "fundamental time", in my approach is the fundamental idea of passage or flow of time, and your "geometric time" would be my "clock time". The difference is that I allow for a more general set of graphs (ideas in platonic framework) in order to introduce intelligent observers.

Chia-Hsiung Tze wrote on Dec. 9, 2008 @ 05:40 GMT

Dear Fotini,

I very much enjoy your essay. Your viewpoint finds resonance in this line from Vladimir Nabokov

”...I cannot imagine Space without Time, but I can very well imagine

Time without Space”

Lawrence B. Crowell wrote on Dec. 10, 2008 @ 19:04 GMT

I ponder whether it is possible to have a duality between time and space, where on one side time disappears and on the other time disappears.

L. C.

Greg Keaton wrote on Dec. 15, 2008 @ 22:32 GMT

Wow. This is an amazing essay. For the first time, I'm able to imagine what a pre-geometry might look like, and how ordinary spacetime might be derived from it. Thank you for your contribution-- I'm voting for you!

T H Ray wrote on Dec. 16, 2008 @ 17:16 GMT

Fotini,

Thanks for a superior and thought-provoking essay!

May I ask, though, in what way do the properties of mu-atter differ from a supersymmetric string, such that string ontology can be obviated?

Tom

Narendra Nath wrote on Dec. 21, 2008 @ 09:47 GMT

Fotini,

another novel way to imagine the truth behind 'reality'. If i may say so science has not created the Universe, it only explains the natural phenomena to understand the manifested observed facts. Best is to develop a single theory to explain everything. But such attempts through Super-string theory and others have also been imperfect in some other ways. The best theory will be one that explains all observed facts with minimum of parameters and assuming concepts that the human mind finds widely acceptable. We being imperfect. our theories too are far from perfect. That is how svcience will continue to progrss for we the professionals to find somethings to do to earn our living. But real physics of the old days was developed through pure curiousity and depth of philosophy the human mind is capable of evolving. We are somewhat becoming soft on that approach in the modern days. We are doing lot of Physics and our number is also going up. But we are working more and more perapheral in our approach. Whatever, mathematical technique we happen to become fammiliar with , we quickly apply the same to solve an isolated unsolved problem in Physics. We need to develop the breadth of the whole Physics while trying to innovate something new in today's Physics. Please excuse me if i sound harsh at my age but please believe me good Physics is at my heart and not my individual glory of what i do in Physics. That is how big Physics may come out even from youngsters like you. You inherit the Big names of the past in Physics already!

John Matthewson wrote on Jan. 20, 2009 @ 18:41 GMT

Very well written. Thank you.

I expect you have seen Linder et al's double slit in time experiment (http://arxiv.org/abs/quant-ph/0503165v1) and the interpretation by Horwitz (http://arxiv.org/abs/quant-ph/0507044 ). There seems to be rash of these cunning laser experiments.

M. Medwin wrote on Feb. 1, 2009 @ 20:48 GMT

I believe the concept of time is tied to space because change can only take place in space. It is simply a way to represent that fact conceptually. It doesn't mean "time" is essential to the constitution of space.

sunray wrote on Feb. 17, 2009 @ 23:10 GMT

Dear Fotini

I don't know if you answer the comments, but i would like to know which essay other than your own do you like best among those posted here?

Also a personal question, does the Srace/Time dynamic evoke for you an inseparable duality, or can you find subtleties where they are co-manifest?

Do you see the dominance of visual rather than accoustic qualifiers as determinant in the dual conception of distance and timing?

Harmonics happen as timing for instance, and their 'polyrythmic' rates do account for various states of matter. Space then could be nothing more than a resonator, or a visual mirror of events resonating in time.

what do you think?

Narendra Nath wrote on Feb. 23, 2009 @ 05:05 GMT

Never posted on your esaay as i needed to assimilate the matter in depth. having done that i note that you have not responded to any of the previous comments made on your meritorious essay. Perhaps you have not been able to find time. In case, you make a brief response, i have some queries to post for you here or on your Internet ID,if intimated!

amrit wrote on May. 15, 2009 @ 06:39 GMT

Dear Fortini

Time is run of clocks in space, space-time is a math model only. I miss in discussion here distinguishing between physical time that is run of clocks, math time that is symbol t in equations and psychological time that is a mind structure.

Aether Wave Theory is based on duality of time and space and it enables to understand the motivations and predictions of both atemporal, both aspatial Universe concepts.

Marcel-M. LeBel wrote on Aug. 3, 2009 @ 22:19 GMT

Fotini,

I am asking you. How in the world could I ever miss this contest? Everyone I ever dealt with on the subject of time is represented here.

I agree with your “no space” conclusion. Of course, this subtraction leaves us only with time. My approach is metaphysical and leaves behind the observer and his perception while retaining the information that is about the universe, not about the observer himself. My model of the universe describes it as being made of only one substance or explosive process we associate with the passage of time. A single substance is operational under simple logic. My study shows that spontaneous motion is an illogical situation in the process of resolution. Since the universe evolves spontaneously by itself, it must be an illogical situation that also started with an illogical situation i.e. a contradiction.

A contradiction is contrary statements at the same time. It is one and zero at the same time. It is like answering yes and no to the same question. (Try saying yes and no with the same word!). But, one can say yes, change his mind and say no to a question. Each statement is acceptable and yet, globally it is a contradiction.

A global contradiction is acceptable if the two statements (or states) are “insulated” by time.

The metaphysical statements are; something exits and nothing exits. We now understand that this contradiction may become acceptable if time separates the two statements or states. One more thing. What ever that exist must be at all time “insulated” from nothingness in order to avoid the true “at the same time” contradiction.

Only one substance can effectively both exist and insulate at the same time. This substance is time itself! In other words, a universe spawn by a contradiction can only be made of time. The insulation of this (any) contradiction by time is a sort of symmetry breaking, the consequence of which is a logical explosion; a universe entirely made of contradictions given that time is the basic background.

This is a primer to the beginning of the universe. Good luck!

Marcel,

Lev Goldfarb wrote on Aug. 12, 2009 @ 23:47 GMT

Dear Fotini,

I simply want to draw your attention to my FQXi essay (submitted less than a week ago), whose abstract I conclude with

"Moreover, ETS suggests the primacy of the new temporal representation over conventional spatial representation, and it is not difficult to envisage that the latter is actually instantiated on the basis of the former, as has also been suggested by some quantum gravity researchers."

You are, of course, one of those "quantum gravity researchers" ;-) ,

and I initially learned about your ideas from your FQXi essay.

Best wishes,

--Lev

Tom wrote on Sep. 6, 2009 @ 14:29 GMT

Well, I'm late to the scene here..

but I found your essay very interesting.

I like your assessment of why time appears

to be the central problem in integrating the

Einstein continuum and quantum mechanics.

I think the pure gravity solutions of general

relativity pose an insurmountable obstacle only

in an abstract theoretical sense, because spacetime

and energy, as Einstein's metric 'says', exist ONLY

as connate, reciprocal counterparts: no matter/no time.

So fundamental time does exist, because we have matter,

and I agree, space is just a theoretical artifact. But

I think you're missing the essential connection between

time and gravity... singularityshuttle.com

0=v.i. wrote on Sep. 8, 2009 @ 07:47 GMT

Fotini,

your essay is going forward our thinking trying to move us to the imaginary virtual world where "imaginary" dimensions (like fundamental time) are "measurable" while "real" dimensions (like space) are converted to the unconceptive (and “umeasurable") dimension.

In other words time is the forth imaginary dimension (unconceptive, unmeasurable, ...) in the real reference system where the three spatial dimensions are real (conceptive, measurable,...). Instead, in an imaginary reference system: space is converted to the one collective real dimension (unconceptive, umeasurable, ...) leaving the other three imaginary dimensions (conceptive, measurable,...) to be determined (one of witch may be the fundamental time).

Everthing depends on how you see it.

synpan.blogspot.com (in Greek)

narsep wrote on Sep. 8, 2009 @ 10:16 GMT

By the way a naive question from a non phsicist (to experts):

If

in what sence these four quantities are consindered independent to each other resulting to a four dimensional space-time

Buz Craft wrote on Sep. 13, 2009 @ 15:04 GMT

Sir, I agree and suggest that Time/All exists at the infinitesimal pulse of Present Time (i.e., with each pulse being the creation of a neoteric Universe)--while the necessary Anti-Pulse is, as you propose, simply Space/Zero! One, then, should consider that Energy/TIME = Mass/TEMPERATURE!

Astro wrote on May. 17, 2010 @ 13:21 GMT

This paper was a look into the future.

Fotini surely did inspire me in her paper. Moreover, is generally beautiful in the sense that we can somehow look past the immaculate bonds of geometry and time. I believe Fotini was absolutely correct in stating that the final theory will not be interested in the geometry of space, since quantization mathods seem to be indicating that degrees of freedom are inherently a world for subatomic, pointlike particles i.e. dimensionless manifestations.

Fotini - well done!

computer geek replied on Oct. 20, 2010 @ 16:19 GMT

The mechanism to generate space is nice here, but the same mechanism can also generate time. Only causality is needed for that.

In computer science exist many different models of time. First is Universal Continuous Time. It is the one people usually think as time, it is the same everywhere and measured by real numbers. Can be interpreted as time coordinate. But it does not exists, sorry about that. Second is Discrete Time, advancing by discrete ticks and measured by integer numbers that count ticks. It is better, classical single processor computer is well described by it. The main property is that tics can be counted, but there is no information about how long they are, meaning two different sources of ticks cannot be compared. This give the next time model, the Branching Time. This model systems that consist of multiple interconnected computers. Each computer have its own ticks, but periodically two ones synchronize by exchanging information. This create network of ticks with occasional synchronization points that make also some common metrics possible. If to look from far then it converge to the first model, to the Universal Continuous Time. Thus revealing mechanism of how Universal Continuous Time may be created.

So, the time together with space may be created as network of occasional synchronization of normally not synchronized events. The light and other massless carriers fit well for synchronizing agents.

Matthew Marsden (London) wrote on Jun. 11, 2011 @ 12:35 GMT

I'm guessing this forum is waning, but none the less if you are interested in this topic you may find my site interesting...

http://www.abriefhistoryoftimelessness.com/

What I am suggesting here is that perhaps it makes sense not to first ask 'does Time exist?', or 'what is Time?' because even these innocent questions are leading.

Instead perhaps we should ask 'what do we directly observe?' and then 'is this enough to explain all that we see ?(and attribute to time)'.

It seems to me that we directly observe 'objects' that can move and interact, and that this is enough tot explain all that we attribute to 'time' existing.

- especially if we see that matter (just) existing and interacting is enough to explain how we seem to accumulate a collection of memories that grow in a linear way.

( see https://sites.google.com/site/abriefhistoryoftimelessness/basic-timelessness/the-past/-x--plaining-away-the-past).

M.Marsden

KHALID MASOOD wrote on Jun. 1, 2012 @ 11:57 GMT

Dear Fotini,

I have independently created “TIME THEORY OF EVERYTHING”.

My main research interests are Physics, Modern Cosmology , Philosophy, Particle physics, Relativity, Time, Theory Of Everything and Economics.

My interests are very broad, extending from origin of the Universe and the origin of life, to the deeply philosophical.

My main research interests are Physics, Modern Cosmology , Philosophy, Particle physics, Relativity, Time, Theory Of Everything and Economics.

My interests are very broad, extending from origin of the Universe and the origin of life, to the deeply philosophical.

I like to ponder the big questions of existence: How did the universe begin? What is the destiny of mankind? Is there a meaning to the universe? and includes the nature of time, the properties of black holes and quantum field theory.

TIME THEORY OF EVERYTHING

[Time Cosmology: Time to re-study Time.]

Created and Written by KHALID MASOOD

TIME THEORY OF EVERYTHING is The Time Universe Theory.

I propose, only Time exists in the Universe. Only Time exists and all that exists is Time.

At the heart of physical sciences is physics, and at the heart of physics is Time. The Universe itself or the laws of nature are time.

Time Creates Space, Life, Consciousness, and the Universe itself. You, the computer, everything is part/form of time.

Time is the only entity. Our classical and modern view of the physical world is wrong.

Time tells matter how to create, matter tells time how to survive!

No particles, no waves, not both and no vibrating or dancing strings. Only "FLUCTUATING EXTREME LEVELS OF ENERGY" write Everything of the Universe, including our consciousness and also Theory of Everything!!!

The only truth about the physical universe is that the universe is not physical. Life and matter of the universe, is nothing but a physical illusion.

The smartest phenomenon of the universe is the universe itself.

On the whole universe is shapeless, massless and weightless.I CAN PICK IT UP!!!

Space is omnipresent, the essential and main component of all matter,the most tangible of all tangibles. Time and gravity are perceptions,tangible temporally but not universally,expanding universe testifies to the infiniteness of space but intangibility of gravity. Time loses meaning beyond the fringes of universe but space endures.